A user group including eight NIH funded investigators requests $1,457,908 to purchase a Three-Dimensional Structured Illumination Microscope (3D-SIM) from Applied Precision, LLC to be housed in the Department of MCB/College of Biological Sciences Imaging Facility. 3D- SIM is one of a small number of recently developed super-resolution microscopy methods that offer the first significant resolution increases in light microscopy in over a century. 3D- SIM offers all the experimental advantages of light microscopy (e.g., ease of sample preparation, molecule-specific labeling of multiple components and relatively fast sample throughput) while providing resolution improvements previously only available from electron or x-ray microscopy with their very restrictive sample preparation and labeling conditions. We intend to use the 3D-SIM as an experimental bridge between already existing state-of- the-art facilities for digital fluorescence microscopy and cryo-electron microscopy within the MCB Department. This instrument will allow research projects that are well developed at the light microscopy level, but require higher resolution spatial information, a complimentary path to relatively slow EM analysis. We provide dramatic demonstrations of the potential of this approach using preliminary data collected on a prototype instrument at Applied Precision on April 15th and 16th, 2009. Analysis of samples using 3D-SIM from three Major PIs on this proposal provide significant new higher resolution detail that will accelerate the advancement of research in these labs and open up new lines of investigation. Management of the proposed instrument will be integrated into the existing, successful Imaging Facility management scheme coordinated by a PhD-level scientist and guided by a departmental imaging committee. The MCB/CBS Imaging Facility currently serves a very large number of UC-Davis researchers (80 researchers in 19 departments paying $113,906 for 2523 hours of use in fiscal year 2007-2008) and many of these existing users will find the 3D- SIM useful. An instrument of this complexity and maintenance cost requires modification of our existing and fiscally-solvent management schemes which we detail in the proposal. This scheme includes an annual commitment of $25,000 towards the service contract from the MCB Chair.